/*
 * Copyright 1999-2017 Alibaba Group Holding Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package studio.raptor.sqlparser.util;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Reader;
import java.io.StringWriter;
import java.io.UnsupportedEncodingException;
import java.lang.management.ManagementFactory;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Properties;

public class Utils {

  public final static int DEFAULT_BUFFER_SIZE = 1024 * 4;
  private static Date startTime;

  public static String read(InputStream in) {
    InputStreamReader reader;
    try {
      reader = new InputStreamReader(in, "UTF-8");
    } catch (UnsupportedEncodingException e) {
      throw new IllegalStateException(e.getMessage(), e);
    }
    return read(reader);
  }

  public static String readFromResource(String resource) throws IOException {
    InputStream in = null;
    try {
      in = Thread.currentThread().getContextClassLoader().getResourceAsStream(resource);
      if (in == null) {
        in = Utils.class.getResourceAsStream(resource);
      }

      if (in == null) {
        return null;
      }

      String text = Utils.read(in);
      return text;
    } finally {
      JdbcUtils.close(in);
    }
  }

  public static byte[] readByteArrayFromResource(String resource) throws IOException {
    InputStream in = null;
    try {
      in = Thread.currentThread().getContextClassLoader().getResourceAsStream(resource);
      if (in == null) {
        return null;
      }

      return readByteArray(in);
    } finally {
      JdbcUtils.close(in);
    }
  }

  public static byte[] readByteArray(InputStream input) throws IOException {
    ByteArrayOutputStream output = new ByteArrayOutputStream();
    copy(input, output);
    return output.toByteArray();
  }

  public static long copy(InputStream input, OutputStream output) throws IOException {
    final int EOF = -1;

    byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];

    long count = 0;
    int n = 0;
    while (EOF != (n = input.read(buffer))) {
      output.write(buffer, 0, n);
      count += n;
    }
    return count;
  }

  public static String md5(String text) {
    byte[] bytes = md5Bytes(text);
    return HexBin.encode(bytes, false);
  }

  public static String read(Reader reader) {
    try {

      StringWriter writer = new StringWriter();

      char[] buffer = new char[DEFAULT_BUFFER_SIZE];
      int n = 0;
      while (-1 != (n = reader.read(buffer))) {
        writer.write(buffer, 0, n);
      }

      return writer.toString();
    } catch (IOException ex) {
      throw new IllegalStateException("read error", ex);
    }
  }

  public static String read(Reader reader, int length) {
    try {
      char[] buffer = new char[length];

      int offset = 0;
      int rest = length;
      int len;
      while ((len = reader.read(buffer, offset, rest)) != -1) {
        rest -= len;
        offset += len;

        if (rest == 0) {
          break;
        }
      }

      return new String(buffer, 0, length - rest);
    } catch (IOException ex) {
      throw new IllegalStateException("read error", ex);
    }
  }

  public static String toString(java.util.Date date) {
    if (date == null) {
      return null;
    }
    SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    return format.format(date);
  }

  public static String getStackTrace(Throwable ex) {
    StringWriter buf = new StringWriter();
    ex.printStackTrace(new PrintWriter(buf));

    return buf.toString();
  }

  public static String toString(StackTraceElement[] stackTrace) {
    StringBuilder buf = new StringBuilder();
    for (StackTraceElement item : stackTrace) {
      buf.append(item.toString());
      buf.append("\n");
    }
    return buf.toString();
  }

  public static Boolean getBoolean(Properties properties, String key) {
    String property = properties.getProperty(key);
    if ("true".equals(property)) {
      return Boolean.TRUE;
    } else if ("false".equals(property)) {
      return Boolean.FALSE;
    }
    return null;
  }

  public static Integer getInteger(Properties properties, String key) {
    String property = properties.getProperty(key);

    if (property == null) {
      return null;
    }
    try {
      return Integer.parseInt(property);
    } catch (NumberFormatException ex) {
      // skip
    }
    return null;
  }

  public static Long getLong(Properties properties, String key) {
    String property = properties.getProperty(key);

    if (property == null) {
      return null;
    }
    try {
      return Long.parseLong(property);
    } catch (NumberFormatException ex) {
      // skip
    }
    return null;
  }

  public static Class<?> loadClass(String className) {
    Class<?> clazz = null;

    if (className == null) {
      return null;
    }

    try {
      return Class.forName(className);
    } catch (ClassNotFoundException e) {
      // skip
    }

    ClassLoader ctxClassLoader = Thread.currentThread().getContextClassLoader();
    if (ctxClassLoader != null) {
      try {
        clazz = ctxClassLoader.loadClass(className);
      } catch (ClassNotFoundException e) {
        // skip
      }
    }

    return clazz;
  }

  public final static Date getStartTime() {
    if (startTime == null) {
      startTime = new Date(ManagementFactory.getRuntimeMXBean().getStartTime());
    }
    return startTime;
  }

  public static long murmurhash2_64(String text) {
    final byte[] bytes = text.getBytes();
    return murmurhash2_64(bytes, bytes.length, 0xe17a1465);
  }

  /**
   * murmur hash 2.0, The murmur hash is a relatively fast hash function from
   * http://murmurhash.googlepages.com/ for platforms with efficient multiplication.
   */
  public static long murmurhash2_64(final byte[] data, int length, int seed) {
    final long m = 0xc6a4a7935bd1e995L;
    final int r = 47;

    long h = (seed & 0xffffffffl) ^ (length * m);

    int length8 = length / 8;

    for (int i = 0; i < length8; i++) {
      final int i8 = i * 8;
      long k = ((long) data[i8 + 0] & 0xff) //
          + (((long) data[i8 + 1] & 0xff) << 8) //
          + (((long) data[i8 + 2] & 0xff) << 16)//
          + (((long) data[i8 + 3] & 0xff) << 24) //
          + (((long) data[i8 + 4] & 0xff) << 32)//
          + (((long) data[i8 + 5] & 0xff) << 40)//
          + (((long) data[i8 + 6] & 0xff) << 48) //
          + (((long) data[i8 + 7] & 0xff) << 56);

      k *= m;
      k ^= k >>> r;
      k *= m;

      h ^= k;
      h *= m;
    }

    switch (length % 8) {
      case 7:
        h ^= (long) (data[(length & ~7) + 6] & 0xff) << 48;
      case 6:
        h ^= (long) (data[(length & ~7) + 5] & 0xff) << 40;
      case 5:
        h ^= (long) (data[(length & ~7) + 4] & 0xff) << 32;
      case 4:
        h ^= (long) (data[(length & ~7) + 3] & 0xff) << 24;
      case 3:
        h ^= (long) (data[(length & ~7) + 2] & 0xff) << 16;
      case 2:
        h ^= (long) (data[(length & ~7) + 1] & 0xff) << 8;
      case 1:
        h ^= (long) (data[length & ~7] & 0xff);
        h *= m;
    }
    ;

    h ^= h >>> r;
    h *= m;
    h ^= h >>> r;

    return h;
  }

  public static byte[] md5Bytes(String text) {
    MessageDigest msgDigest = null;

    try {
      msgDigest = MessageDigest.getInstance("MD5");
    } catch (NoSuchAlgorithmException e) {
      throw new IllegalStateException("System doesn't support MD5 algorithm.");
    }

    msgDigest.update(text.getBytes());

    byte[] bytes = msgDigest.digest();

    return bytes;
  }

  public static void putLong(byte[] b, int off, long val) {
    b[off + 7] = (byte) (val >>> 0);
    b[off + 6] = (byte) (val >>> 8);
    b[off + 5] = (byte) (val >>> 16);
    b[off + 4] = (byte) (val >>> 24);
    b[off + 3] = (byte) (val >>> 32);
    b[off + 2] = (byte) (val >>> 40);
    b[off + 1] = (byte) (val >>> 48);
    b[off + 0] = (byte) (val >>> 56);
  }

}
